High technologies are progressed abruptly, especially for the technology of manufacturing processes of micro-electronic product, so computer is prevalent into every family and enterprise and becomes an indispensable electronic product in modern lives. Following the popularity of computer multi-media, it is required more peripheral products for input and output. The technologies of optical-electronics and semiconductor are improved daily such that the product technology of relative peripheral devices of computer such as optical scanner etc. are sophisticated daily and make the optical-electronic devices be more and more popularized and have already become required products among peripheral devices of computer. Wherein, the optical scanner has further become an important peripheral device of input and output for computer. The optical scanner mainly applies a light source module to provide light source for scanning document, and also applies an optical-path device to receive reflective document image during the scanning procedure of the light source module. Again, the document image is retrieved by the charge-coupled device and converted into digital signals through an optical-electronic transformation. Finally, the digital signals are transferred into computer for proceeding image treatment.
Please refer to FIG. 1A, which is an illustration of three-dimensional structure of an embodiment of an optical scanner of typical flatbed type with upper lamp module commonly seen in current market. Mainly, a document window glass 12 is arranged at upper side surface of the outer shell 11 of an optical scanner 1 for placing a reflection-typed document (not shown). An optical chassis 14 is driven by a driving apparatus 13 to make a linear motion along the direction of a guiding rod 15 inside a hollow outer shell 11 to proceed an image scanning job on a reflection-typed document (not shown) placed on the document window glass 12. The document window glass 12 may be placed by a transmission-typed document 31 or a transparency-placing frame 3 arranged with a plurality of transmission-type documents 31. An upper lamp module 2 from upper direction provides a light source 21 emitting light onto the transmission-typed document 31. The optical chassis 14 is driven by the driving device 13 to make linear motion along the direction of the guiding rod 15 inside the hollow outer shell 11 to proceed an image scanning job on a transmission-typed document 31 placed on the document glass window 12.
Please refer to FIG. 1B, which is an illustration of three-dimensional structure of an embodiment of an optical scanner of typical flatbed type with upper transparency cover device commonly seen in current market. Wherein the upper transparency cover device 5 is arranged with at least one lamp 51 for providing the required energy to an upper transparency cover 52. After the upper transparency cover 52 has accumulated the energy, it becomes a light source that may provide light from the upper portion incident upon the transmission-typed document 31. The document window glass 12 is placed with an auxiliary fame 6 that may prevent the light that is provided by the upper transparency cover 52 and is emitted from the upper portion from being scattering to make sufficient energy of light source be incident upon the transmission-typed document 31. Again, the optical chassis 14 is driven by the driving device 13 to make linear motion along the direction of the guiding rod 15 inside the hollow outer shell 11 to proceed an image scanning job on a transmission-typed document 31 placed on the document glass window 12.
In summarizing above description, when executing a scanning job on transmission-typed document 31, since different kind of transmission-typed document 31 has different kind of transmittance, so certain transmission-typed document 31 may show particularly clear image and also other transmission-typed document 31 may show less clear image. Therefore, how to execute an optimal result of scanning job has become an urgently pursuing solution for the relative industries and makers of optical scanners.